On another note, I listen to TWIP while driving home on the Sticher phone app, which much like a radio, lets me listen to a list of my favorite, frequently updated podcasts (news & health-related in my case), and alerts me when there is an updated episode. The audio podcasts are small enough that I stay under my allotted cell minutes and don’t have to download or delete episodes. I actually discovered TWIP via the Sticher app about three years ago, and while I have no financial connection to the app, had never heard you mention it as a conduit for TWIP.

Keep up the good work.AllanKailua-Kona, Hawaii

Richard writes:

My guess is P. vivax malaria. The patient has fever every other day (tertian fever) with shaking chills, general malaise and headache, and the labs are all consistent with malaria. This could be either a recurrence (with the symptoms of the primary infection masked by mefloquine treatment) or a long incubation period (maybe due to the thalassemia minor). Either way a 6 month asymptomatic interval is, I think, not unusual with vivax. Add primaquine!-RichieColumbus, OH

Richie writes:

Hey guys, I am loving TWIP 2.0! I am a medical student considering a career in infectious disease and tropical medicine in particular; TWIP was always great but the added clinical component has improved it. I also love the commitment to more frequent episodes.

Regarding the case presentations: I like the structure in #82 with Daniel supplying the basics and Dickson and Vincent asking follow-up questions, but is there any way you guys could limit the "guessing" at that point? I personally think it would be more fun to just present the history and selected other findings, and then save the differential diagnosis for the following episode. For example, the discussion of the first and second cases included the correct diagnoses. I don't yet know the answer to the third case but I was pretty sure it was vivax even before Dickson began talking about why that was probably it. I think it would be more satisfying to form a diagnosis from the presentation alone. If I'm wrong and it is not vivax, well, that undermines my point entirely and please disregard this email.

RichieColumbus, OH9F, -13C

TWiP 83 case:

Jan writes:

Dear doctors,

Thanks to google, I think it's lymphatic filariasis, transmitted by the culex mosquito. Love the (twix) show(s) where I learn a lot outside my normal field which is trees. We still are in the dark ages there. Our treatment options after diagnosis are rather limited; improve the soil, let's wait and see, amputation or euthanasia. Sadly it's mostly the latter due to economic reasons.

GreetingsJanps The weather here in Rotterdam, the Netherlands is 7 degrees centigrade and showery, wind is not too bad for a change.

Elise writes:

Dear TWIP Trifecta,

I am a longtime fan of yours and think you’re terrific both as a duo and a trio. Thank you so much for your work. I am not a scientist at all, but I love listening to you and do my best to follow both TWIP and TWIV out of pure interest.

Of course I have been following along with your recent case studies and have taken notes and done my own, non-scientific, non-academic, searches to try to diagnose these patients. I was privately pleased that I figured out the Babesiosis diagnosis in the gentleman on Long Island by myself but did not write in due to embarrassment.

With this new case, I am feeling reckless, having gotten one right. I think the gentleman from Guyana may have Lymphatic Filariasis. Here’s why:

The nematode worms that cause the disease are common in Guyana and this gentleman didn’t drink filtered water or take other precautions.

An infection can take years to manifest while the worms multiply and many infected people are asymptomatic, so he wouldn’t have had cause to complain about much, which he hasn’t done (and in what is behavior somewhat typical of many men I know, he still didn’t feel he wanted to do much about it even with significant swelling and an open wound).

Dr. Griffin did say that the man’s genitals were normal, and while it is apparently common for the genitals to also become swollen, perhaps this man is fortunate (since not all people who are infected have this symptom), or the disease had not progressed.

The edema described in patients with later stage Lymphatic Filariasis matches the sort that Dr. Griffin described, non-pitting and “brawny,” with skin color and texture changes.

In reading about Lymphatic Filariasis, I was a bit confused because there is not always a mention of a chronic abscess or wound, but apparently a single abscess can be caused by collections of dead worms on the lymphatic tract, so that symptom fits.

I was interested to see that, for diagnosis, blood collection should be done at night because that is the time when the microfilariae are circulating. Does this mean that diagnoses are often missed because blood is most often drawn during the day or is there so much suspicion about what is causing this constellation of symptoms that medical practitioners know to draw blood for this diagnosis in the evening hours?

Thank you very much for your webcast. If I get this wrong, I hope very much that my having written is not something embarrassing (to me), and if I get it right, or close to right, or wrong in an interesting way, perhaps it is due to the way you explain everything so well and are such good teachers that even someone with no training could play at-home detective.

It is very cold here in Lower Manhattan where I am right now, -5C, 23F.

Best wishes,

Elise

Ken writes:

Hi Vincent, Dickson and Daniel,

I have been listening to the TWiX series for a long time, and even got to experience the TWiV bump by appearing in an episode of TWiV when Vincent visited MedImmune last year.

Having done postdoc work in a trypanosome lab at the Univ of Buffalo, I particularly enjoy TWiP and am really enjoying the recently revamped format. During episode 83, you were talking about primaquine and a MASH episode in which it was discussed. The character was Klinger, who was a Lebanese American. According to what I found on Wikipedia (not always a reliable source, but I think in this case it is) hemolysis is an adverse effect of primaquine in Africans or Caucasians of Mediterranean descent.

Also, I wanted to take a stab at the case study in episode 83. My diagnosis is lymphatic filariasis due to Wuchereria bancrofti. I would recommend doing blood collection at night since the filaria circulate at night in the blood and then doing a smear for identification.

Didn't write in last week because the time course threw me off of malaria, which was my only suspect. The epidemiology, time course, and some of the syndrome is right for elephantiasis secondary lymphatic filariasis. However, while lymphatic filariasis may produce numerous bacterial infections, I would anticipate these to either be short-lived or ultimately proceed to sepsis. As such, I anticipate that the persistent, unhealing, painless wound would demonstrate leishmania amastigotes under tissue sample light microscopy.

At this stage in the disease, it's clear that at least some of the worms have died, which complicates testing, but he may show some microfilarea in a thick blood smear if the sample is taken at night and some worms persist. Check for splenomegaly and preform an Ig assay to rule out visceral leishmania, refer the patient to a lymphatic specialist for possible elephantiasis therapies, active filariasis has been known to respond to doxicycline (since we're on the cheap), and treat the leishmania with miltefosine.

Wink writes:

At 1:11 I'm saying Wucheratia bancfofti.Wink from Atlanta(P.S.: The vivax was at 9 months)

Bill writes:

TWIP Trifecta,

I love the new format with the case studies.

I came across the TWIX trio a few years back, and they give my mind a welcome diversion during my commute to and from work where I spend my days managing a team of talented engineers in the auto industry.

I was disappointed to see just one response to last weeks case, so I thought I would give it a shot.

This weeks case sounds like lymphatic filariasis - a.k.a. elephantiasis. It is recognizable by Lymphedema - commonly called big foot. The decreased lymph system function causes the build up of fluid, and makes infection more likely. The open sore seems to be a secondary bacterial infection.

Regarding tests to schedule, I would like to see a thick blood smear with a H&E stain collected as late as possible - this should help to confirm the presence of microscopic nematodes.

There are currently three known vectors – Aedes aegypti, Culex and Anopheles – in Guyana that can transmit the disease. Vincent's question on the swollen genitals would suggest ruling out Wuchereria bancrofti, but in my literature search, it was not clear if Brugia malayi and Brugia timori are prevalent in Guyana, so perhaps it could still be W. bancrofti.

On to treatment, Diethylcarbamazine (DEC) looks to be the drug of choice. An alternative could be ivermectin to kill the microfilariae with doxycycline to take care of the adult worms.

For the open wound - antibiotic to clear the infection.

Many Thanks,BillBuffalo, New York.

Weather - Very cold, lots of snow but no risk of mosquito bites.

Jesse writes:

I really enjoy TWIP, both the entertaining banter and the science. I particularly enjoy Dick's expositions on the myriad parasitic ecologies. Daniel's clinical expertise is a welcome compliment to Vincent and Dick's tributes to Abbott and Costello. Thanks Vincent, for supplying Dick with a new microphone and coaching his microphone technique. As a turnabout, a video of Dick teaching Vincent how to cast with a fly rod, while unrelated to parasitism, would make for bemused viewing.

Here's my take at episode 83's listener quiz. From perusing my wife's medical references I'll venture that the Guyanan gentlemen with the discrete travel plans is suffering from lymphatic filariasis. He has probably been infected for many years as the swollen leg's skin has "brawny" characteristics.. According to my reference text the lack of genital involvement, swelling limited to the lower leg, and an ulcer along his inner shin point to an infection by Brugia malayi. I don't recall Daniel's physical exam mentioning enlarged popliteal lymph nodes but I imagine they were present.

I look forward to listening to your next episode to learn if my guess is on the mark. Thanks again for a great podcast.

Robin writes:

My four episodes of malaria were in childhood before my teens, in East Pakistan (now Bangladesh) and West Pakistan (now Pakistan). That's the closest we come to cohabiting with a photosynthetic organism: the malarial parasite is descended from a lineage of photosynthetic Dinoflagellates and still carries in its genome a few vestiges from its ancestral photosythetic machinery.

A far cry from corals and free-living non-photosynthetic microbes which associate with photosynthesisers that act as symbionts, endosymbionts and even become acquired organelles.

Some New Guinea tribes had a 95% prevalence of asymptomatic malarial parasitemia in adults. The prevalence among adults in Gambia was 70+%. If in deep time past the parasite could have found a way to ride along through the vertebrate germ cell line, they might have found a way to earn their keep, and become an endosymbiont.

Old wives' tales: these are best spread by GYN specialists.

Swollen leg: The patient usually does not worry if the condition is painless.

Night time thick and thin blood smears from a finger stick, Giemsa stained, could be examined.

First thing to treat elephantiasis is a course of penicillin or other related drugs if the patient is not allergic to them. Prompt attention with treatment for episodes of local cellulitis and special attention to local hygiene and cleanliness to prevent cellulitic episodes can be very helpful.

Albendazole with ivermectin should deal with the microfilariae. Doxycycline against Wolbachia should permanently eliminate microfilariae and halt progression of elephantiasis.

If the ulcer looks like leishmaniasis and shows no improvement with PCN, a PCR is in order, but since it is not reportable, neither the CDC nor the state health department would be persuaded to pick up the tab. The physician may bill TWIP (Take What Insurance Pays) but the laboratory service is another matter.

Meanwhile fluconazole may be an option until laboratory results. Miltefosine may be a consideration then.

Oscar writes:

That was a sneaky way to get someone to listen to the back episodes! Well played Dr. Griffin, well played.

Also, keep up the experimentation! You all have good instincts, follow them. The world needs a new cartalk (weekly, enlightening mysteries). You could do it. At least three different mysteries presented and solved per episode. There are some back episodes where Dixon and Vincent trade off questioning each other through the whole presentation and it really works. Instead of the car talk guys questioning the listener you question each other and it steps the listener through the paper.

Here are some free ideas--instead of 'case' or 'paper' or 'presentation' I'm going to use the term 'mystery'.

1. All three of you should laugh at least three times per episode. 2. Instead of listeners call in, have a 'smarter person than us' call out (perhaps to enlighten a mystery or present a mystery or share news or report on location), that parasitalogist from Mayo--Bobbi Pritt, that you had on a couple months back would make great regular--not too often and not too long--like when some professor from MIT would call in to yell at Tom and Ray. 3. Figure out what kind of mysteries the bit you're doing is--figure out some sort of taxonomic classification. Get a few solid kinds so you and the listeners can start to catch a rhythm.4. Know how much of the mysteries you want to give away going in.5. Have at least one mystery that goes on for more than a week, maybe an easy and a hard one. Perhaps the 'smarter person than us' could give all three of you a mystery that is outside your expertise and even outside the scope of parasitology. The Car Talk hosts weren't afraid to blindly grasp for an automotive engineers solution to a relationship problem that had nothing to do with cars--you shouldn't either--it keeps you extra human.6. Here's a mystery presentation idea: 'One Question'. Give a really short background and have people email (or perhaps fill out a form) where they get to ask a question and take a guess. If they get it the first week on the first question they get lauded. If they ask a question and guess wrong it goes to the next week with a new person where the short presentation (one or two sentences) and then a summary of all questions and the new person gets to ask a question and guess. The longer it goes the better the prize? If all three of you took turns coming up with the mystery you could compete with each other as well as to who could stump the listeners the longest.... oooh... I like 'stump'. Maybe you could call it 'Chump-The-Stumps!' for a shameless-but-not-copyright-infringing homage to Cartalk.7. Have fun!

On another more trivial subject, why is the title of the show “This Week in Parasitism”, and not “This Week in Parasitology”? When I was growing up, my mother worked in a hospital lab, and that department was called “Parasitology”. One of your other podcasts is called “This Week in Virology”. Just wondering why the different nomenclature.

Thanks for all the enjoyable episodes. It’s fun to learn new stuff.

Dani writes:

Hello Twip Musketeers!

I love the new case of the week, thank you for this most interesting addition to your educational empire.

I am e-mailing today about lizards and lyme disease, I've recently learned that some lizards that are a host for tick nymphs actually clear the nymph of the lyme spirochete. Nature amazes me! I've done a literature search looking for information on the biochemical basis for this phenomenon with no luck. What do you guys know about this? Is this phenomenon useful for trying to manage Lyme?

The weather is 16 C in sunny Cupertino, but I prefer the rain. Thank you for the fantastic podcast!

I like your idea of a TWIP coffee mug prize (or maybe a mug discount).

In this second case study you presented, the present symptoms are pretty vague, but his history is interesting. Also since with this podcast you’ve given us license to hunt for zebra’s…particularly parasitic ones...

I would want to rule out Rocky Mountain Spotted Fever common in Long Island, but with the presence of regular blood transfusions and a spenomegaly in his history makes me think you were highlighting something more. I would want to also test for transfusion-associated Malaria, dengue and babesiosis.

Although normally vanishingly rare as a transmission route in the US, the fact he’s getting monthly transfusions, moves this route to just very unlikely. I think there were several dozen transfusion-associated Babesia cases back in 2002 and I actually thought the US was testing for it now. Otherwise its just opportunistic if around cattle and deer ticks. Between malaria and dengue, I doubt the patient would describe dengue as just fatigue, malaise and stomach upset. I’ve had both and dengue hurts worse than that.

So if I had to guess, it might just be Malaria (non P. falciparum).

I look forward to learning more from you three in such an entertaining forum.

Best regards,

Allan

Allan Robbins, DIH, MPHUniversity of the NationsKailua-Kona, HI

Curt writes:

Hey TWiP gang, loving the new format. This case sounds like a dead ringer for transfusion acquired malaria. Test by PCR or slides, treat with antimalarials.

Thanks,-Curt

Robin writes:

A case of transfusion-carried malaria.

Anne writes:

Dear Daniel, Vincent and Dickson,-

I have only recently discovered TWIP and the other TWIX and have been avidly listening to both the current episodes and catching up on the earlier ones (if only I had a longer commute.) As a veterinary pathologist, it has been a delight to hear about diseases and pathogens near and dear to my heart and training.

Regarding the second clinical case presented by Daniel on January 24, 2015:I considered Babesia microti and Anaplasma phagocytophilum high on my list of differentials which included all of the diseases discussed on the show: Babesiosis, RMSF, and malaria plus anaplasmosis, ehrlichiosis, typhoid fever, and even bartonellosis. Given the patient’s history of regular blood transfusions, the issue of whether the infection was acquired through tick bites was less important than whether a classically tick borne infection could be acquired through the blood supply. Similarly, although several of these are not caused by ‘eukaryotic parasites’, I figured they were still fair game since RMSF had been thrown in the mix.

A diagnosis of infection with Babesia microti is supported by the generalized and vague signs of illness, fever, history of asplenism, dark urine, mild elevation of liver enzymes, and geographic location of patient. Similarly, these findings would also support a diagnosis of human granulocytic anaplasmosis (HGA) for which transmission through the blood supply has also been documented. Favoring consideration of HGA is the presence of thrombocytopenia as well as anemia. Were morulae observed on the blood smear?

Although the presence and nature of a rash would not have been diagnostic in and of itself, it is a sign to be considered in several of these diseases.

Looking forward to hearing the answer.Anne

Anne Lewis, DVM, PhDDiplomate, American College of Veterinary PathologistsHead of Pathology ServicesBeaverton, OR

Robin writes:

Dear Doctors of TWIP,

Long time listener to all of the shows, first time writing to you.

My guess for the case presentation is babesiosis, aquired via blood transfusion. That is what will be seen on the smear I suspect.

I very much enjoy the clinical application aspect of the show. I am a registered nurse (32 years) and amatuer biologist. Dickson's anecdote regarding the effectiveness of freezing bear meat will make for great nerd cocktail conversation. Thank you Dickson!

As part of my job I am resposible for monitoring and following approximately 50 patients per month for possible blood stream infections secondary to vascular access devices for example PICC lines.

I also recently "diagnosed (thanks to TWIV)" a collegue with dengue from travel history and symptoms. I use word diagnose in the loosest possible sense.

Your shows have been a great source of learning for me. Thank you for sharing your time and talent with all of us.

Kind regards,

Robin

Varun writes:

Greetings Profz,

There is often a reference made to the connection between Toxoplasma and Schizophrenia, which has come up again in TWiP 79. There is a great deal of debate in literature. I have also blogged about it sometime ago. I have referenced Vincent's page in the post. As someone currently doing some experiments in psychoneuroimmunolgy of schizophrenia, I'm currently looking at it. Keeping my fingers crossed.http://varuncnmicro.blogspot.in/2014/05/does-toxoplasma-drive-you-crazy.html

Second point that came up in response to letters was regarding methanogens. As you know there is a huge interest in "microbiome", and methanogens is also one of them researched upon. There was a correlation made between M smithii and Obesity. I have blogged about that also a time ago. I'm not aware of recent developments though.http://varuncnmicro.blogspot.in/2013/02/say-hi-to-methanogens-in-human-flora.html

Last but not the least, I enjoy Dickson's every episode. He is an excellent science narrator. I (With thousands of others around the globe) just wish, he keeps giving more shows and gets TWiP100 within the end of 2015. As always, you profz are excellent educators.

Thank you for your podcasts,

Varun C N

Junior Research FellowNational Institute of Mental health and NeurosciencesBanaglore, India

Peter writes:

Dear TWiP hosts,

Congratulations to your new addition. I am looking forward to future TWiPs with more clinical perspectives.

Speaking of which, are you considering to get Alfred Sacchetti on TWiP?He has been on TWiV and TWiM; two of my most favorite episodes. It has been a while: TWiV 132: Virology 911 on 08 May 2011 and TWiM #22: Microbiology 911 on 14 Dec 2011.

If there are not enough parasites in the ER to fill a show, maybe he could also return to TWiV and/or TWiM.

I really would like to listen to a show Parasitism 911, if there is enough to talk about.

And lastly, from 09 Feb 15 Duke University's course Tropical Parasitology: Protozoans, Worms, Vectors and Human Diseases starts on Coursera (see https://www.coursera.org/course/parasitology). I enrolled and hope to find the time to keep up with the course during the eight weeks of study.

Thanks for all your work.

Kind Regards from Incheon (Korea),

Peter

Cindy writes:

I am sitting here listening to the newest twip that happens to be "living in a wormy world" and watching tapeworm segments crawl out of my sleeping dog's bottom. Fascinating. Definitely time to get to the vet, the dogs have been catching and eating rabbits lately. I'm thinking Taenia pisiformis. Sometimes I wish life wouldn't so closely imitate art.

Anyway, thanks for the informative podcast. I think it is responsible for desensitizing me enough so I didn't lose my lunch.

TWiX is reaching people like me, a non-scientist stay at home mom who enjoys following science as a hobby. Along with "Skeptics Guide to the Universe" they are my most eagerly anticipated podcasts.

Steve writes:

Hi Vincent,

First let me say that I'm totally addicted to your podcasts, and often find myself listening to them almost round the clock. I'm pretty much housebound with a long term illness, and you and Dickson, and the team, make a great contribution to keeping me the right side of sanity. You must be providing one of the best scientific educational resources on the Web: long may you continue.

For want of science literate doctors in the NHS, I've been dumped in a pigeonhole labelled either 'ME', or 'hypochondria', depending on the preferences of the GP one sees. I think that both are just handy labels that get the profession off from proper consideration of all the signs and symptoms, and that the majority of people like me would be properly diagnosed if only they could deal with scientists instead of GPs.

In this respect, I find myself quite envious of those who come to your research hospital and get the kind of careful consideration shown in your new case studies. If only there was somewhere like that here in England, but I'm afraid there is very much an anti-scientific, anti-testing culture in the medical profession here: the more clues, in terms of signs and symptoms you provide, the more likely you are to be called a hypochondriac without considering them at all.

Anyway, it's good to know *somewhere* there is a scientific approach!

Because of this curious anti-science attitude here, a number of patients have actually started to conduct their own investigations, and I thought that Dickson in particular, might like to look at the link, below, to some of the microscope work that one of the more gifted patients--Peter Kemp--has been doing. I have suggested to him before that‎ he might find some people to help him at the AMA. I don't know if he did get in touch, but, from the presentation below, I think you might agree that he is doing quite well on his own!

I have caught up to all the TWIPs! Finally! Sorry this may be a long email as I have had 80+ episodes to think.

I have been listening to your show while living in Japan. I have been teaching English here since I graduated from undergrad with a degree in biochemistry.

As an undergrad, I stumbled upon the opportunity to study parasites when I attended a professor's research presentation. The information was so fascinating and novel I worked up the courage to ask, as a freshman, if there were any opportunities to work in her lab. Amazingly I was accepted and will forever be grateful for the mentorship I received as a novice. I worked on characterizing Trypanosome DNA binding proteins as therapeutic targets for the next 3 years. There I was "infected" with an interest in parasites/infectious disease.

I decided to pursue a higher degree in the communicable disease microbiology. I applied and was accepted to the University of Tokyo Graduate School of Medicine international health sciences Masters program. I'll be working on Trypanosome mitochondria complex ll as a chemotherapeutic target in the Department of Biomedical Chemistry.

The program starts April 2015 and so I have been following all the TWIX in order to keep my brain on point. I'm also reading a lot of related literature. I am now finishing Dr. Hotez's book, Forgotten People, Forgotten Diseases, which is an absolutely fantastic overview of NTDs and the public health issues from a drug development standpoint. I really hope you guys can have him on the show again! His journal PLOS NTDs is fantastic as well and he regularly writes interesting public health review pieces on various topics.

You guys have mentioned the Meguro Parasitological Museum in Tokyo, the only parasite museum in the world. I have been twice and its a great place. It's free and they have great visual exhibits like phylogenetic trees and many many preserved samples (while most text is in Japanese).

I was amazed to learn more about the huge impact Japanese researchers have had and continue to have in the field of parasitism and related fields.

Finally I must admit, I too was starting to lose interest in TWIP recently but the addition of Dr. Griffin has really reenergized the broadcast. Dr. Griffin's expertise really brings out new expert participation from Dr. Despommier as well. (Whereas anecdotes/ life cycles were starting to be repeated a lot.) Maybe I felt I understood the life cycles and characterization of the main parasites well enough therefore I was ready for more clinical experience to combine with them.

Also a question, I missed some of the first TWIM and TWIV shows. Is there an easier way to get these earlier shows than going through the TWIV website and downloading from each episode page?

Please continue to get knowledgeable guests and hosts on!Thanks so much for your efforts,

Russell

ps I wanted to add I'm an mid-twenties American and thus I appreciate the punny banter on this and all of the other TWIX podcasts. Even when Dickson tries to stump Vincent with pop culture trivia that seems to go well over my head....

Our weather today is 79ºF and clear but we have just experienced a record 25-year overnight low of 54ºF, (FREEZING, as few of us have either a heater or air conditioner in our home or office, one wears their hoody and socks to bed and work this time a year.)I know… we’re pitifully wimpy.

I AM intrigued by your proposed inclusion of a medical case study….as long as it does not diminish your famous narrative diversions and rabbit trails.

My clinical training and work was in and exclusively for, practice in areas of the world most challenged by access to health care, setting up and strengthening local Primary Health Care. So my diagnostic thought process went as follows.

As diagnostic tests are always at a premium if available at all in these settings, the medical history and exam became especially important as was the clinical gestalt of elder medical practitioners. The left flank pain initially made one think UTI, but when ruled out, the intermediate abdominal pain and finding of a liver “cyst”, next made one think of an amebic liver abscess and a round of tinidazole (which also does NOT go well with alcohol).

As your stated tests results indicated a more fluid filled cyst than an amebic abscess, I would have last started considering Echinococcus or hydatid disease. She had the opportunity of infection, but it should have been confirmed by the ELISA. However some 10-20% of cases are false negative. I didn’t recall what the findings were for the kidney or spleen, which are more left flank. Still a few months of albendazole and or mebendazole every two weeks might both bring symptomatic relief and narrow the diagnosis. But I may still be missing something.

I appreciate you highlighting symbiotic infections that need multiple species to cause pathology, when the presence of just one may often be benign. I think this understanding illuminates a number of conditions.

Here are my thoughts on the case study posed by Daniel Griffin in TWiP #80

The description of the large fluid filled cyst in the liver matches cystic echinococcosis. The patient history indicates high risk for cystic echinococcosis and I was unable to find any other plausible causes for the cyst.

Echinococcosis is progressive and in untreated cases it has a high mortality rate. Given that her history indicates high risk for cystic echinococcosis in terms of risk/benefit, it would I think be advisable to treat the patient for that.

A suitable treatment would be to give albendazole for several weeks, followed by puncture of the cyst under ultrasonographic guidance and aspiration of some cyst fluid for examination by light microscope. The microscope examination is to observe for the presence of viable protoscolices. If they are present, echinococcosis is confirmed and the cyst is aspirated completely.

"At this point, exclude possible connections of the cyst with the biliary tree by means of injection of contrast medium in the cavity. If no connections are evident, a scolecoidal agent, usually hyper-tonic sodium chloride solution or ethanol, is injected and left for a variable period (usually 5-30 min) and then re-aspirated. The destruction of protoscolices can be observed in fluid sample aspirated after the injection of a scolecoidal agent. This sequence is termed PAIR (puncture, aspiration, injection, re-aspiration). As happens with drug therapy, positive responses include both a decrease in cyst size and a progressive change in echo pattern (generally solidification) "

Once the risks of anaphylactic shock and secondary cyst formation been reduced (eliminated?) by the use of albendazole and scolecoidal agents, the large size and location of the cyst would probably warrant surgical removal.

As a precaution albendazole is recommended be continued for 2 months postoperatively.

I have read that some inoperable cysts are left in place. What are the advantages of surgery to remove the dead cyst? Would there be more risk of complications from surgical removal or leaving the dead cyst was left in situ (I presume that in time the dead cyst would become calcified)?

Rebekah writes:

Dear TWIP Doctors,

I have been wanting to write again for sometime, but the recent new design of the podcast really gave me the motivation. I was already happy to see the new episode, since TWIP is my favorite of the TWIX series, but the explanation of the new design really got me excited. I know I will not know all the answers, since I see very few parasites working in a small hospital in Michigan, the question really got me searching and thus learning more than I would on my own.

Before I reveal my answer to the case study I would like to share a story of my own. This was a specimen submitted on Halloween night 2014 (more like Saturday morning). A woman was concerned that she had passed a large worm in her stool, so she came into our ER with a jar of stool. The ER staff brought me the jar. My thought was that I would sort through it and try to pick out the worm or any possible proglottids that might be present. I would then clean it off to give to the pathologist for review on Monday. As I was sorting through the specimen I noticed that there was a large ribbon-like object in the specimen, so I transferredsome of it to a Petri dish and started to clean it off with some saline to reveal...PAPER TOWEL! Upon further investigation I came to realize this specimen was not stool. As a person who has seen and worked with MANY stool samples, my expert opinion is that this was strained beef stew (or equivalent, as I saw a cubed potato and a piece of parsley) with strips of paper towel mixed into it. After that, I had a very interesting conversation with the ER Physician and the ER staff sent me another specimen which was a Tapeworm they made out of paper for me, so we all had a good laugh. I am sure Dr. Despommier and Dr.Griffin have similar stories of this kind of behavior. I thought you would get a kick out of it.

Now for my answer to the case study, after much searching I still believe this is an infection with Echinococcus. I was a bit thrown because of the serological test being negative but after looking in to it further I saw that the sensitivity of the test was around 80%, so it is very possible that a false negative could have been the reason for this. I also read that the liver is the most common organ involved and that most symptomatic cysts are larger than 5cm, so it makes sense that her cyst, being smaller, would not be causing symptoms. I also read that imaging studies may not be conclusive if daughter cysts and hydatid sand are not present. I don't remember mention of these things, so I thought they likely were not present. For all of these reasons I believe the diagnosis of Echinococcus is correct. Even if I am wrong I had a lot of fun trying to work this case out! Thank you so much for this wonderful podcast.

Rebekah MLS (ASCP)MicrobiologyPennock Health ServicesHastings MI

Damon writes:

Doctors,

You guys are great! I have listened since the beginning and enjoy all the information you provide. It has only been a mere 32 years or so since my last biology class (high school) and I'm surprised at how much basic information I have retained. Anyway, I listened to TWiP 80 today (14 Jan) and I think I know the parasite that the woman from Bangladesh carried around with her. I really perked up when I heard that she helped her father with his sheep for about three months while visiting Bangladesh. Then I reviewed TWiP 7: Tapeworms are fantastic!, and decided that she had gotten dog tapeworm(s) from her father's sheep dogs. I can only assume that this parasite can lay dormant for years (a little over three years in this case) before becoming active. I am assuming that in the dormant stage there would be no indication of the parasite's presence using the various detection methods. Were the lab results the same in May as they had been in January? Do physicians prescribe "anti-worm" drugs without a definitive diagnosis? If so, then I suppose one could prescribe the most effective drug with the least probability of bad side effects. Would it be unethical to treat for a disease in which the patient has no symptoms? Oh, and the lower abdomen pain… unrelated to the parasite?

Thank you so much for the podcast!

Damon

Justin writes:

Since I used to work in a clinical animal laboratory doing hematology and urinalysis (VCA Antech) I'd say this still sounds like it could be a(n) helminth (although maybe I should stop presuming all developing" areas have "worm" issues....) so maybe treat with a broad spectrum vermicide such as Benzimidazoles... I guess if you do the biopsy you might also release eggs/larvae of whatever it is so that sounds bad.

I have no idea which kind of helminth but I remember many of them escaped parasitology and serology a lot so many were found by GW staining or wet mounts; even found tapeworm eggs once in a urinalysis because the infestation was that bad for the dog and/or just contaminated (I found no bacteria so I doubted the contamination).

Robin writes:

In CE, surgery remains the primary treatment and the only hope for complete cure. Better forms of chemotherapy and newer methods, such as the puncture, aspiration, injection, and reaspiration (PAIR) technique are now available but need to be tested. • Chemotherapy in CE ◦ Indications: Chemotherapy is indicated in patients with primary liver or lung cysts that are inoperable (because of location or medical condition), patients with cysts in 2 or more organs, and peritoneal cysts. ◦ Contraindications: Early pregnancy, bone marrow suppression, chronic hepatic disease, large cysts with the risk of rupture, and inactive or calcified cysts are contraindications. A relative contraindication is bone cysts because of the significantly decreased response. ◦ Chemotherapeutic agents: Two benzimidazoles are used, albendazole and mebendazole. Albendazole is administered in several 1-month oral doses (10-15 mg/kg/d) separated by 14-day intervals. New data for continuous treatment are emerging from China. The optimal period of treatment ranges from 3-6 months, with no further increase in the incidence of adverse effects if this period is prolonged. Mebendazole is also administered for 3-6 months orally in dosages of 40-50 mg/kg/d. Limited data are available on the weekly use of praziquantel, an isoquinoline derivative, at a dose of 40 mg/kg/wk, especially in cases in which intraoperative spillage has occurred. Albendazole has been found ineffective in the treatment of primary liver cysts in patients who are surgical candidates.[5] ◦ Monitoring: Monitor patients for adverse effects of agents every 2 weeks with a CBC count and liver enzyme evaluation for the first 3 months and then every 4 weeks. Monitoring albendazole and mebendazole serum levels is desirable, but few laboratories are capable of performing this measurement. Imaging studies are required for follow-up on the morphologic status of the cyst. ◦ Outcome from medical treatment of CE: Response rates in 1000 treated patients showed that 30% had cyst disappearance (cure), 30-50% had a decrease in the size of the cyst (improvement), and 20-40% had no changes. Also, younger adults responded better than older adults. ◦ Contraindications: Because chemotherapy is the only treatment in certain cases, contraindications are limited to early pregnancy and severe leukopenia. Chemotherapeutic agents and patient monitoring are the same as with CE, but the length of treatment is different. ◦ Outcome: A significant increase in 10-year survival rates exists in patients receiving chemotherapy compared to patients who are not (85-90% vs 10%, respectively). • PAIR in CE: The Puncture Aspiration Injection Reaspiration (PAIR) technique is performed using either ultrasound or CT guidance, involves aspiration of the cyst contents via a special cannula, followed by injection of a scolicidal agent for at least 15 minutes, and then reaspiration of the cystic contents. This is repeated until the return is clear. The cyst is then filled with isotonic sodium chloride solution. Perioperative treatment with a benzimidazole is mandatory (4 d prior to the procedure and 1-3 mo after). ◦ The PAIR technique can be performed on liver, bone, and kidney cysts but should not be performed on lung and brain cysts. The cysts should be larger than 5 cm in diameter and type I or II according to the Gharbi ultrasound classification of liver cysts (ie, type I is purely cystic; type II is purely cystic plus hydatid sand; type III has the membrane undulating in the cystic cavity; and type IV is the peripheral or diffuse distribution of coarse echoes in a complex and heterogeneous mass). PAIR can be performed on type III cysts as long as it is not a honeycomb cyst. ◦ Indications: Inoperable patients; patients refusing surgery; patients with multiple cysts in segment I, II, and III of the liver; and relapse after surgery or chemotherapy are indications for the PAIR technique. ◦ Contraindications: Early pregnancy, lung cysts, inaccessible cysts, superficially located cysts (risk of spillage), type II honeycomb cysts, type IV cysts, and cysts communicating with the biliary tree (risk of sclerosing cholangitis from the scolecoidal agent) are contraindications for the PAIR technique. ◦ Outcome: The reduced cost and shorter hospital stay associated with PAIR compared to surgery make it desirable. The risk of spillage and anaphylaxis is considerable, especially in superficially located cysts, and transhepatic puncture is recommended. Sclerosing cholangitis (chemical) and biliary fistulas are other risks. Experience is still limited, but early reports are supportive of this technique if the indications are followed.

◦ The indications and type of surgery are different for CE and AE. ▪ Cystic echinococcosis ▪ Indications: Large liver cysts with multiple daughter cysts; superficially located single liver cysts that may rupture (traumatically or spontaneously); liver cysts with biliary tree communication or pressure effects on vital organs or structures; infected cysts; and cysts in lungs, brain, kidneys, eyes, bones, and all other organs are indications for surgery. ▪ Contraindications: General contraindications to surgical procedures (eg, extremes of age, pregnancy, severe preexisting medical conditions); multiple cysts in multiple organs; cysts that are difficult to access; dead cysts; calcified cysts; and very small cysts are contraindications. ▪ Choice of surgical technique: Radical surgery (total pericystectomy or partial affected organ resection, if possible), conservative surgery (open cystectomy), or simple tube drainage of infected and communicating cysts are choices for surgical technique. The more radical the procedure, the lower the risk of relapses but the higher the risk of complications. Patient care must be individualized accordingly. ▪ Description of surgical procedure ▪ The basic steps of the procedure are eradication of the parasite by mechanical removal, sterilization of the cyst cavity by injection of a scolicidal agent, and protection of the surrounding tissues and cavities. ▪ Scolicidal agents include formalin, hydrogen peroxide, hypertonic saline, chlorhexidine, absolute alcohol, and cetrimide. A variety of complications have been described with all scolicidal agents, but in the authors' experience, 0.5% cetrimide solution provides the best protection with the least complications. Other scolicidal agents are 70-95% ethanol and 15-20% hypertonic saline solutions. A report by Ochieng'-Mitula and Burt in 1996 on the injection of ivermectin in the hydatid cysts of infected gerbils revealed severely damaged cysts with no viable protoscoleces.[6] Further evaluation of this scolicidal agent is needed. ▪ At surgery, the exact location of the cyst is identified and correlated with the radiologic findings. The surrounding tissues are protected by covering them with cetrimide-soaked pads. The cyst is then evacuated using a strong suction device, and cetrimide is injected into the cavity. This procedure is repeated until the return is completely clear. Cetrimide is instilled and allowed to sit for 10 minutes, after which it is evacuated, and the cavity is irrigated with isotonic sodium chloride solution. This ensures both mechanical and chemical evacuation and destruction of all cyst contents. During this process, care is taken to ensure no spillage occurs to prevent seeding and secondary infestation. ▪ The cavity is then filled with isotonic sodium chloride solution and closed. Rarely, omentum is needed to fill the cavity. The cyst fluid is inspected for bile staining at the end of the evacuation and irrigation process. The inside of the cyst is inspected, and any bile duct communication is sutured. In case of infected cysts with biliary communication, closed suction drainage is required. Regardless of whether an open or laparoscopic approach is chosen, these basic principles must be followed in order to ensure the safety of the procedure. ▪ Medical requirements: The medical staff at the treating center should have experience with treating CE. Concomitant treatment with benzimidazoles (albendazole or mebendazole) has been reported to reduce the risk of secondary echinococcosis. Treatment is started 4 days preoperatively and lasts for 1 month.

Christian writes:

Dear Professors Racaniello and Despommier,

I want to draw both your attentions to an exciting new resource for researchers studying parasitic worms! WormBase-Parasite is a new public database with genome data for more than 80 helminth species. Below are links to the press release from the Wellcome Trust Sanger Institute and to WormBase-Parasite itself.

We investigated a trichinellosis outbreak associated with wild boar consumption. The index patient sought healthcare multiple times before being diagnosed. Targeted education of hunters and consumers handling wild game or free-range pork, owners of game farms, and clinicians is warranted.

WinkAtlanta

Robert writes:

Sorry for replying to an old episode, but I thought you might want the following information if you haven't heard it from anyone else yet.

Fiona who wrote in referring to "rope worms" said she was using MMS enemas to treat them.

Here is some added information that MMS (miracle mineral supplement) refers to a handfull of different chlorine dioxide evolving solutions, and the usual dosing being increasing doses until the side effects require backing down (oraly until you can no longer avoid emesis, or as enemas until diarrhea). The "rope worms" seem to be sloughed off intestinal mucosa.

MMS has been linked to deaths both due to side effects and delay or refusal of proven treatments for various diseases. While the eponymous miracle mineral solution has been banned in various markets people continue to buy the chemicals that can be used to generate chlorine dioxide and dose themselves in the hope of dealing with their various medical problems. I hope Fiona is doing better, and no longer using chlorine bleach internally.

Robert S.ps: thank you for your ongoing efforts to produce the "this week in" podcasts.

It shows the extraction of a bizarrely long worm from a praying mantis. It's hard to believe that the mantis was still alive with that thing in it. At first this was just a cringe-worthy video that I wanted to share with TWiP as maybe a listener pick of the week, but then I read a bit about the parasite, which turns out to be a nematode called a horsehair worm. It's a very interesting parasite, and one of those that alters host behavior (which has been discussed several times on TWiP). It's a parasite of arthropods and infects beetles, cockroaches, grasshoppers, and even some crustaceans.

I haven't delved very deeply into the life-cycle, but I read that the adults are free-living in freshwater but somehow their eggs find their way to their arthropod hosts and, eventually, infection with have an effect on the host's brain which drives it to seek water and drown, thus releasing the adult form of the worm.

These fascinating "mind-altering" parasites have been discussed on TWiP in the past, but I think it would be fun to have an episode dedicated to a vast array of these bizarre and, in some cases grizzly, examples of how parasites affect their host's behavior. Another example, which I think has been mentioned in passing on a previous episode, is Cordyceps (https://www.youtube.com/watch?v=XuKjBIBBAL8).

Anyways, I'd like to say that I greatly enjoy TWiP and all of the other TWiX podcasts (particularly TWiV, since viruses are my main area of interest) and I am always eager for the next episodes to arrive. I admit, I'm one of many who would love a more frequent TWiP schedule, but I understand that you're both very busy, so I suppose monthly-ish will be enough to give me my parasite fix.

Kindest regards,Erik

Jeffrey writes:

Hey Twippers,

I am really excited about the new format and the addition of Daniel to the team. It seems like he will add a really interesting perspective to the talk - and maybe some great tangential stories (which I love, by the way).

I recently saw an article about the paper linked below on Science Daily and thought it might be worth a discussion on TWIP. It is about the possibility of bed bugs being a vector for T. cruzi. I would love to hear your opinion on what implications these results could have on the transmission of Chagas disease.

When I read it I thought of the two you. I suffered from migraines for years, I'm so glad that it wasn't a tapeworm!

It is rainy and 50F here in Seattle just the way I love it!

I too am sad about the Car Talk brother's, Tommy, passing. He was such a joy!

Take care!

Wink writes:

Loved the last TWIP, and all the rest. I had read long ago that vivax relapses occur with a periodicity of 3 months; not necessarily every 3 months, but multiples of 3 months. Is this true?

WinkAtlanta, GA

Øystein writes:

Dear Vincent Racaniello and Dick Despommier,

I just read an intriguing article on the parasite Cryptosporidium, that concludes:"The observation of extracellular developmental stages in this study further supports suggestions that classification of Cryptosporidium as an obligate intracellular apicomplexan may require revision"

The story of this parasite is unfolding before our eyes. Maybe you would like to revisit this parasite again on your show. Cryptosporidium research is generating more interest than before because of the new evidence from the Global Enteric Multicenter Study (GEMS) that Cryptosporidium ranks as the second most important cause of severe childhood dirrhoea after rotavirus.

If the parasite can replicate in biofilms growing on the inside of our water pipes we might have a bigger problem than we realized.

I still follow all your TWIX family shows with great pleasure, and have been following you since the very beginning. Thank you again for your inspiring podcasts.

Hey, my name is Sharmbey (SB) in College Park, MD. I started listening to TWIP in August 2014 in order. As I type I'm on #52. It's been extremely entertaining hearing you guys talk so much mess to each other, yet so humble every time. Perfect. I'm not a student or working in any type of science field but I love all science. Dr.D, I've been thinking of "tall buildings to grow crops" for years before I knew other people actually started it. Finding you was mind-blowing with your fancy "vertical farm". :-) If you guys read this it will be awesome to hear my name by the time I catch up to the episode. I can clearly see you guys have plenty of content so I wont ask "dont stop". In episode #52, a listener tells of a great grandparent sick with malaria in the past. That reminded me of the book As I Lay Dying where a dying mother or grandmother rode in a wagon on a long trip. Maybe they had malaria in the book. Just a random thought. Anyway, keep up the great work. Oh yeah. You don't need me to tell you, but I want to say "forget" that guy or anybody who comments on your style. Tell as many stories, related or unrelated, as you like. Who's names are on the title?? Like I said, you guys are the perfect blend of a wealth of knowledge and some comedy. Vince bashes Dickson, while Dickson is humble about it. Then Dickson is like more rough and gruff and more crude, in a good way, while Vince tries to defend the subject at hand. Great stuff. I probably won't write again so I'm getting it all out now. I'm a delivery driver with La Prima Catering and I go to Walter Reed, NIH, NASA, NOAA, UMD very often and its so cool hearing what's going on in these places. I think I'm done. SB out.

On a side note, it seems TWIP does not have facebook presence. Unless that depends on my poor searching ability you may want to consider rectifying that.

Best regards,

--Jesper

Simon writes:

Dear Professors,

Firstly I would like to share with you the attached photograph. I was in London a few weeks ago waiting to meet a friend in Cavendish Square, which is right next door to the Royal Society of Medicine. In order to kill time I was walking around the square and I noticed a blue plaque on a nearby house (they are quite common in London denoting places of historic interest). As soon as I saw it, I knew I had to take a picture to send in to you, particularly as I have recently been listing to the series of episodes on malaria from the early days of Twip.

Interestingly, the data seem to suggest the key role of olfaction in nematode host identification, and this reminded me of your discussion on TWiP 78 of odor detection by mosquitos. The fact that both mosquitos (as carriers of malaria), and these skin-penetrating nematodes have evolved sensitive olfactory responses led me to wonder if this is a very common host detection strategy among free-living/moving parasites? Do you know of other examples?

Thank you in advance for your comments.

Simon

Anne Marie writes:

I went to Belize this summer and noticed the attached sign at a roadside tamale place. I thought you two might appreciate seeing it. I don't know if you guys speak Spanish so I thought I'd translate it as best I can:

"For a community free of Leishmaniasis

These are diseases caused by a parasite called Leishmania that transmit to humans through sand fly bites.Wear a thick, long-sleeved shirt, thick pants, a hat with a wide brim and work boots in the forest or jungle.Keep you house clean, ordered and free of trash and weeds.Keep animals (including dogs and cats) out of the house, in clean, secure places.Use fine mesh mosquito nets daily. Cover yourself after dark and cover children after 5 pm.Go to the nearest Health Service, TREATMENT IS FREE."

Also: my dad got ehrlichiosis while orienteering in Maryland. He felt cruddy for a long time but had no lingering ill effects. (He's also been bitten by a rattlesnake!)

My best,Anne Marie

Abe writes:

Hi,

I just started binge-listening to all the episodes of TWIV and TWIP from the beginning. These are great! As an interested scientist in a completely different field, I wanted to ask:

TWiP: Are there any examples yet of Archaea acting as parasites to hosts in the other kingdoms? If not, are there specific biochemical reasons why it would be impossible?

Yours,Abe

Chelsea writes:

Hi Vincent and Dickson,

I hope this e-mail finds you both well! I am a big TWiP fan - the podcast is fantastic for getting good science across in an entertaining way. I'm even assigning several of your episodes to students in my "Ecology of Human Parasites" course at UMich!

I'm attaching info on an opportunity for early career scientists to present their work on "ecosystems within organisms" - any aspect of ecology and evolution of the microbiome. This Early Career Scientists Symposium will be held at UMich in late March. Many of your listeners may be excellent candidates, so I would be very grateful if you could mention the call for nominations on your next episode.

Keep up the great work!

Christophe writes:

Hi Guys,

I saw this article and thought it would interest Dickson (assuming he hasn't seen it already)

I have two "corrections" for you. First, in episode 2, Prof Despommier named Darwin's Bulldog as Aldous Huxley. The correct Huxley is Thomas Henry Huxley. Aldous was a much more recent philosopher and writer of fiction.

Second, in episode 17 (Entamoeba histolytica) - which I'm only half way through - polar ice melt and consequent sea level rises were mentioned. Prof Despommier's explanation for the difference in effect of melting at the north and south poles was not really right. The real difference is that the ice at the north pole is almost all floating sea ice, so it's already displacing a mass of water equivalent to the mass of the ice - thus when the ice melts, it will have no nett effect (ignoring the warming of the water which would result in some thermal expansion). The antarctic ice, however, is most sitting on top of the vast landmass that is the continent of Antarctica. So when it melts, there will be water - and plenty of it - added to the ocean system.

I came to TWiP via TWiV (which I started listening to during the height of ebola news coverage this year). Last week I also added TWiM. I'm slowly working my way through the back catalogue. All of the podcasts have me feeling vague pangs of regret at having left science after graduating. Thank you for making great shows that are accessible, entertaining and educational all at the same time.

My research is focused on the biofilms formation, Motility (swarming and swiming ) and QS in fluorescent Pseudomonas (P. aeruginosa and P. fluorescens).

In laboratory a interaction had been with insect and bacteria metaboliye EPS (so a Bacteriophile insect). I do not know the identity of this namtode, is a parasitism interaction? or symbiosis one , to interprete my figures.Please could you give me it name?

Hope to read you, I ask you to please accept my best wishes.

Thank you very much for Reading my message.

Best regards

Dr. Meliani

Microbial Ecology Professor researcher at the University of Mascara, Algeria

Peter writes:

Dear TWiP teamI saw this report on the BBC and thought it may be worth a mention on TWiP:

A woman was horrified to discover that her nosebleeds had been caused by a leech living in her nostril. Daniela Liverani from Glasgow started having persistent nosebleeds after a backpacking trip around South-East Asia, At first she thought her nosebleeds the result of a motorcycle accident but sought medical assistance when she noticed the nosebleed "had ridges" and had started "poking out" of her nose and wriggling.

I recently finished reading Dickson's book "People, Parasites, and Plowshares'.Looking for further information on the topics covered in the book I found this paper reviewing studies of the effects of helminth infection in reducing the rejection of transplanted tissue.

I have been following TWIP for several years. I am a software engineer and parasitology is only an avocation. As an undergraduate in the early 80's I discovered my love of history of science and ecology, although I continued the path of a software developer. As an adult I read Carl Zimmer's Parasite Rex and became totally fascinated with parasitology. Later I read The Coming Plague by Laurie Garrett. What I love about both Mr Zimmer's and Ms Garrett's writing is how they tie the science to the scientist. I look at The Coming Plague as a masterpiece in history of science with really touching stories of the scientists and their impact on the world.

I'm writing to ask you to make sure that when you talk about the science of parasitology, you keep including the stories of who figured out what and why it was important. The two of you bring a lot of experience in parasitology, microbiology, and virology and have lived the history of it--keep the stories coming!

If you haven't watched this, I recommend that you do. It's a lecture by Prof Walter Munk on his life's work in the field of oceanography. Fascinating!

P.S. I also recommend the book Krakatoa: The Day the World Exploded as a great book with history, anthropology, and science all tied together with history of science.

Mike writes:

Bobbi Pritt was a superb guest. As Vincent commented, 'now we get to hear the pronunciations of the parasites' or something along those lines which I also found helpful. I had almost given up on this podcast because it seems to lack focus and rambles a bit. Hope you are able to get more people like Bobbi on your show.Mike in Oregon

Kyrie writes:

Hi Dixon & Vincent,

Recently I got a wonderful pug puppy from a local puppy mill store ( which I know no one should ever do but I had just lost another dog that was with me for 12 years and I walked by not a puppy trap not in a rational state) the puppy it turns out has demotic mange.

I had read about an oil from India called neem that by some mechanism blocks the reproduction if bacteria, parasites, fungus everything!

I put it on my dog and weird white things started coming off within a half hour. I dusted her off and they came back again 4 times. What is that? I also wash her twice a week with Borox and vinegar.

What do you know about neem oil and its effects on the parasitic life cycle and what can you tell me about demotic mange and their behavior ?

Anything would be helpful. The dog I bought is super cute but has many health issues so I am trying the natural path to reduce complexity.

Also a side note Vincent your are wonderful and fascinating but why so hard on your good friend Dixon?

He seems like such a sweet person sometimes I want to yell as the podcast at you leave him alone!

BTW: I listen to all the twi + x podcasts as I go to sleep every night! Best science podcasts out there. Thank you and all the wonderful people on the show for giving the lay people a little real science.

As a side note, I am a software developer that has zero to do with microbiology outside of the fact that it effects us all. Thank you for the peek into the very small universe it's really fascinating.

I am so grateful!

Thanks for everything you do,

Kyrie

Rebeka writes:

Hello Doctors,

I have just started listening to TWiP and am on episode 20 currently. I had a couple things I wanted to share and I apologize if these are things you have already covered in more recent episodes. First in the episodes regarding Giardia and Entamoeba histolytica it was stated that these are not reportable. Being a Medical Laboratory Scientist (once called Med tech) I do report these to the local health department when we recover them. I live in Michigan, so maybe the regulations are different where you are. I have attached a copy of the MDCH reportable diseases for you.

Also, when I was an undergrad I read an article about a vaccine that targeted the gut of ticks, so that when the tick took a blood meal from an animal the antibodies would be ingested as well and kill the tick. This reduces the amount of ticks in an area and the overall tick borne diseases. I did a quick search and sure enough this research is still going on! What do you think about the possibilities of a vaccine similar against say mosquitoes? Ticks take a larger blood meal, so it might not work, but it is still an interesting idea. Here is the link to the current work :http://www.parasitesandvectors.com/content/7/1/77

I absolutely love the show! I also teach Microbiology to Medical Laboratory Technicians at a community college and I am going to recommend this podcast for them to prepare for their board of certification exams.

Thank you again for the fantastic show.

Rebekah MLS (ASCP)

Erica writes:

Hi

I'm a Zoology graduate currently working in a parasitology lab and applying for molecular parasitology PhDs in Ireland.

Recently found your podcast and really enjoying listening to it in the lab.

Wanted to say thanks, I was surprised at the lack of parasitology podcasts out there and I'm glad you have it covered :)

Would enjoy it if you delved into some parasites of agricultural importance such as PPNs.

Keep it up

Regards

Erica

Alex writes:

Hi guys

Love your twip. Dickson, you mentioned in Twip 76 that H. polygyrus is the best model we have for human hookworm. You might be interested in this paper attached that we recently published which highlights how similar Nippostrongylus and Necator really are in terms of their biology and secretomes. I now think of Nippo as a better model for human hookworm infection than H. poly. Keep up the great work on the show! Thoroughly entertaining and informative.CheersAlex Loukas

Dave from Fresno (that's where I live!) in your emails suggested that DVT may embolise to the brain. If it does, it would indicate an atrial septal defect or a ventricular septal defect: the emboli are too big to traverse the pulmonary capillaries.

Also aspirin and other antiplatelet agents are primarily effective against platelet thrombi, which are aggregations of platelets, like snowdrifts, at sites of rapid flow, viz. arteries. Such thrombi are friable, adherent, and less likely to detach en masse. DVT is more akin to a blood clot in a test tube.

Multiple ring forms of the malarial parasite in an erythrocyte is indicative of Plasmodium falciparum infection.

I just returned from the annual meeting of the International Society of Travel Medicine (ISTM) where I enjoyed many fantastic lectures and caught more Cutthroat Trout fly fishing the upper Snake River during one evening than I could count. I will confess to using a hopper with a bead head dropper to achieve this. I was relaxing on this beautiful Sunday morning with a cup of coffee in hand and the August 1st issue of Science. To my delight I saw that the cover had a colorized scanning micrograph of a dog roundworm (Toxocara canis). This image on the cover directed the reader to a commentary and to two research reports about how infection with parasites influences the immune system in such a way that antiviral immunity is impaired.

I am an MD trained as an infectious disease specialist and am active in the care of immigrants, travelers and indigent patients suffering from infectious diseases. At NYU School of Medicine I received excellent training in parasitic disease from a dynamic visiting professor that has served me well in China, Africa, Nepal and here in the states. My PhD is in Immunology and my early work involved defining the phenotype of human B1 cells, an innate subset of B cells. My current work is on HIV latency in hematopoeitic stem cells. These research reports were thus as they say ‘right up my alley’. The commentary is readily accessible to a broad audience and explains how the two research reports demonstrate that helminth infections induce viral exit from a latent state. The two research reports contain the expected rigor one sees in Science.

These reports seem a perfect crossing of both your areas of focus, Vincent’s expertise in virology and Dickson’s expertise in eukaryotic parasites. Schistosoma mansoni is one of the parasites involved in the first article and one even my kids know about after swimming in Lake Malawi this past winter. Trichinella is used in the second paper and is not only dear to Dickson’s heart but something we still see up in Alaska, where I worked until recently. To fully disclose my fascination with parasites, the discussion my physician friend from Alaska and I were having as we caught cutthroat trout on the Snake last week was about the two cases of acute Trichinosis that he recently managed in a married Alaska couple from eating undercooked bear meat.

I am left thinking that Dickson needs to fish the upper Snake River in Wyoming, but more importantly he might consider writing a monograph entitled not People, Parasites & Plowshares but: Parasites: When Plowshares become Swords!

Sincerely,

Daniel Griffin, MD PhDAssociate Research ScientistDepartment of Biochemisty and Molecular BioPhysicsColumbia University

Malaria prevalenceCan be so high that asymptomatic parasitaemia is the norm: it was 95+% among adults of some New Guinea tribes and over 70% among the adults in the territory of Anopheles gambiae.

French speakersAmong the reasons I am not a French speaker were Horatio Nelson and the Duke of Wellington, to neither of whom I have any affinity or allegiance. But they were among the reasons that the Raj was a British Raj, and not a French one. An important reason also why so many Indians (& Pakistanis) speak adequate if not good English, and little or no French.

Parasites are doomedAs in the answer to the question about Bob Dole in the 1996 presidential election - "Does he wear boxers or briefs?": "Depends". Those that adapt well enough may become a necessary feature, as Dr. Dickson has explained with regard to intestinal parasites and autoimmune disorders of the gut (and perhaps elsewhere). And let's not forget the bacterium that invaded an Archean to produce the great*gazillion grandparent of all of today's eukaryotes. Mitochondria are no longer parasites.

Extra membrane protein in RBC cytoplasmOne reason for it may be to prolong the life of the RBCs. Think of a tire filled with tread that can migrate to the outside as the tread on the outside is worn away. RBCs are subject to plenty of wear as they squeeze through narrow capillaries.

Movement of Homo sapiens and other hominids outside Africa Extincted by human diseaseThere were two (known) non-sapiens lineages outside Africa in later times that we met: neanderthals and denisovans. We may have also met floresiensis but there is no genetic evidence for commingling. Just about all other hominid species were in Africa and were exposed to the infective load found there. Moreover, we coexisted with Neanderthals for ten millennia or more.

Within our species 14 disease-free millennia after crossing the Bering land bridge into the New World and several more disease-free millennia preceding in Siberia helped to make Native Americans susceptible to smallpox and measles, thus enabling settlement of vacated territory by Europeans who brought those diseases as naturally as their ectoparasites.

Homo habilis evolved into NeanderthalI had the impression that it was a more advanced form: Homo heidelbergensis.

Colder climate - invasive speciesThe hairless ape is adapted to year-round tropical weather. Anywhere else it is an invasive species: to survive elsewhere it has a cultural/technological adaptation that proceeded much faster than evolution: shelter & clothing.

Cause of migration civil warNot necessarily. It would be doubtful whether the migration across the Bering land bridge was due to civil war. The migration of Jews out of Europe in the time of the Third Reich was not quite due to "civil" war. Or of Armenians out of their lands annexed by Turkey.

ExtravasationComing out of a vessel (vas=vessel). Could be a tubular vessel such as for blood or lymph, but also a sac-like vessel such as for urine or bile. Malarial parasites coming out of an RBC don't quite cut the mustard.A reminder for the upcoming podcast:Ask parasitologist from Mayo clinic about lice & anemia.

My personal guess is that it would not be due to depletion by volume, but perhaps the adaptation of the body of some substance injected by the lice to act as a signal that causes the body to make the blood less nutritious.

Dear Vince,Long long flight, yes.What is a chief, but invisible, physiodynamic consequence of even short flights?Deep vein thrombosis in lower extremities. Cuts loose as ambulating off plane. Throws embolis to lungs, even heart, brain. Pulmonary embolism is a big deal.Prophylaxis? Wiggle your feet, ankles, calves regularly. Venous return is passive, and hydraulically driven by muscle massage of lower veins in the course of everyday activity.Lack of activity lets blood accumulate above vein valves. Leg bent at knee, and dependent, further kinks veins. Unmoving blood begins clotting, especially in guys of a certain age. If not troubled in flight, they then walk off plane and collapse.To prevent, extend legs, and isometrically flex and extend them even when bent. Get up and about in flight at any excuse, and for none.Alcohol may repress clotting some. At minimally higher risk of uncontrolled bleeding, a bit of aspirin probably wouldn't hurt. Bloody Marys are nutritious.Travel well. Wish I were there.DaveFresno

Tristen writes:

Dear Vincent and Dixon,I'm not sure if you got my email a few weeks ago since I sent it from my personal email and not through the website so I'm sending it again just in case.

I have to tell you that I'm a huge fan of TWiP and I love listening to you guys! In November 2013 I did my first medical mission trip to Nzara, South Sudan. Vincent you probably already know an interesting virology fact about Nzara- it's one of the first places Ebola virus was discovered in 1976. After the short trip I enjoyed the work so much that now I am trying to gain funding so I can leave life here and continue the work in Nzara for a couple years. I appreciate how your podcasts are both educational and entertaining at the same time. My favorite one so far is when you had Peter Hotez on talking about neglected tropical diseases.

You guys should really do an episode about chronic malaria infection in children living in sub Saharan Africa and the connection between Epstein Barr virus and the high rate of pediatric burkitts lymphoma diagnosis. People get tired of hearing about malaria, but this would be a great podcast because it combines parasitology and virology. I find it quite interesting and happen to learn about this connection when I had plasmodium malariae after returning from my trip (despite taking malarone). Thank you both for your good work and for giving me such valuable information which I can take back with me to South Sudan!

In spite of their rather peculiar elliptical shape and other abnormal features (see below), camelid red blood cells are by no means nucleated:

"The elliptical, anucleate erythrocytes of camels have been examined for the presence of marginal bands and their constituent microtubules. Lysis of erythrocytes under microtubule-stabilizing conditions readily revealed marginal bands in at least 3 % of the cells, as observed by phase-contrast and darkfield light microscopy. Microtubules plus a marginal band-encompassing network of material are visible in lysed cell whole mounts with transmission electron microscopy. Marginal band microtubules are also evident in electron micrographs of thin-sectioned camel erythrocytes identifiable as reticuloyctes on the basis of submaximal electron density (reduced haemoglobin iron content) and presence of polysomes. The results suggest that marginal bands may be involved in morphogenesis of camel erythrocytes but are not required for maintenance of their ellipticity after cells are fully differentiated."

“Among the mammals, members of the family Camelidae (camels, vicunas, guanacos, llamas, alpacas) are unique in that their erythrocytes, though anucleate, are elliptical (Andrew, 1965). The question thus arises as to whether MBs play a role in cell shape generation and/or maintenance in these species.”

It seems to be a rather widespread confusion in educational circles, I also succumbed to this false notion during my undergraduate years. Then one day I decided to look up the possible advantages that could offer the presence of nucleated cells in camels. My wild guess was that perhaps those red blood cells could work in tandem with their also rather peculiar subset of homodimeric immunoglobulins G to keep at bay particularly harmful parasites that might have infested those animals at some point. It turned out that it had nothing to do, and the characteristic elliptical shape of their red blood cells are thought to be an adaptation to extreme dehydration and rapid rehydration, and possibly to increase the efficiency for carrying oxygen at high altitude:

In camels (Cohen and Terwilliger):

“The occurrence of MBs in camel erythrocytes is possibly correlated with ontogeny of distinctive physiological properties. Camels are adapted to survive extreme dehydration and rapid rehydration. Their erythrocytes can withstand considerable osmotic stress, responding in a manner more similar to the elliptical, nucleated erythrocytes of non-mammalian vertebrates than to the biconcave diskoidal cells typical of other mammals (Ponder, 1942; Trotter, 1956). Camel erythrocytes are highly resistant to hypotonic haemolysis (Perk, 1963; Yagil, Sod-Moriah & Meyerstein, 1974), exhibit a low rate of water transport (Naccache & Sha'afi, 1974), and are also relatively stable under hypertonic conditions, in which crenation was not observed (Yagil et al. 1974). In addition, very young camels (6 months or less) apparently possess 2 populations of erythrocytes with respect to osmotic resistance: one population with adult-type response, the other with still greater haemolytic resistance (Pe rk, 1966). Direct studies of the possible correlation between occurrence of MBs and osmotic resistance in camel erythrocytes would therefore appear to have potential value for understanding MB and erythrocyte function.”

In llamas (Azwai et al.):

“Llamoid erythrocytes were small (7.32 ± 0.95 × 3.9 ± 0.52 μm), elliptical, flat and their counts obtained in the present study (10.3 to 15.0 ×106/ μL) were higher than those in other domestic animals (FELDMAN et al., 2000). The flat shape and the presence of the few folded erythrocytes were attributed to the low thickness to diameter ratio of llama red blood cells (VAN HOUTEN et al., 1992). The small volume resulted in a high concentration of erythrocytes for any given PCV. The high MCHC of llama (38.6 to 48.0 g/dL) in comparison with those in other species might be due to the flat nature of the erythrocytes, which allowed more space for haemoglobin molecules to increase their efficiency for carrying oxygen at high altitude (HAWKEY, 1975). It was evident that llama bone marrow, unlike other ruminants except dromedary camels (MOORE, 2000), was normally releasing immature erythrocytes, including polychromatic rubricytes, metarubricytes (0.8%) and reticulocytes (0.4%) i nto circulation.”

Maybe you've already done a segment on Toxocara and it's hidden under a clever title, but if you haven't done one so far, would you consider doing a podcast?

I just discovered TWIP and what a treasure trove it is! Thanks for all your efforts.

Best,

Curtis

John writes:

Dickson sometimes mentions how crows eat roadkill. They eat the contents of the animal's intestines, rather than its parasite-infested organs. I witnessed a crow eating a California Ground Squirrel and Dickson's explanation helped me understand that the crow was not playing with its food, but rather being picky.

All I remember that I know is that one time I let my cat endure a heavy flea infestation for an unconscionably long time. I redeemed myself, if at all, by the knowledge that I slept with her a lot, and so endured a share myself (but I'm extraordinarily thick skinned, so it wasn't so bad, and I didn't get plague).

Anyway, the situation's gravity was brought home to me when I discovered that she was significantly anemic. Clearing the fleas and maintaining her freedom from parasites of any kind found the anemia gone and blood restored to a normal hct, hgb after a few months. In other words, the insects consumed a significant quantity of blood.

Lice aren't fleas of course, and people are bigger than cats, so I don't know if the lady who corresponded with you about her and her daughters' lice and her longstanding iron supplementation will have her case at all illuminated by my anecdote, but I do know that fleas can drain a consequential amount of blood from some of us.